Eukaryoute Cell Structure Flashcards
(17 cards)
What is the structure & function of the Nucleus?
• Structure:
• Contains DNA that stores genetic instructions for making proteins.
• Contains a nucleolus, where ribosome subunits are made.
• Has a double membrane with pores that allow regulated exchange.
• Function:
• Separates transcription (DNA → RNA) and translation (RNA → protein) in eukaryotes.
Structure and function of ribosomes
Structure:
• Can be “free” in the cytoplasm or “bound” to the Rough ER.
• Function:
• Catalyse synthesis of polypeptides (proteins) during translation.
• Free ribosomes: make proteins used within the cell.
• Bound ribosomes: make proteins for secretion or membrane insertion.
Structure and function of Rough Endoplamsic reticulum
Structure:
• A series of connected flattened membranous sacs.
• Has bound ribosomes on surface.
• Continuous with the nuclear envelope.
Function:
• Synthesizes polypeptides that are released into the RER lumen.
• Especially involved in producing secretory and membrane-bound proteins.
Smooth endoplasmic reticulum function and structure:
Structure:
• Similar to RER but lacks ribosomes.
• A series of connected flattened membranous sacs.
Function:
• Synthesizes phospholipids and cholesterol.
• Involved in membrane formation and repair.
Golgi apparatus function and destination
Function:
• Modifies polypeptides into their functional forms.
• Sorts, concentrates, and packs proteins into vesicles.
Destinations of vesicles:
1. Lysosomes (for digestion).
2. Plasma membrane (for membrane expansion or embedding).
3. Exocytosis (to secrete proteins out of the cell).
Vesicles structure and funciton
Structure: Membrane-bound sacs.
Functions:
• Transport vesicles: move molecules between cell compartments by budding off one organelle and fusing with another.
• Secretory vesicles: secrete molecules from cell (via exocytosis), Add new phospholipids to the membrane.
Lysosome structure and functions
Structure:
• Small, spherical organelles enclosed by a single membrane.
Function:
• Contain digestive enzymes that work in acidic pH.
• Digest large molecules, damaged organelles, or pathogens.
• Important in immune defense (e.g., phagocytosis).
Mitochondria structure function and origin:
MITOCHONDRIA
Structure:
• Surrounded by a double membrane.
Function:
• Site of aerobic cellular respiration.
• Produces ATP (energy).
Origin: Evolved via endosymbiosis.
Chloroplasts structure, function and origin
Structure:
• Contain light-absorbing pigments like chlorophyll.
Function:
• Capture light energy to convert water and CO₂ into glucose (photosynthesis).
Origin: Evolved via endosymbiosis.
Vacuole structure and function
Structure:
Large central vacuole in mature plant cells.
Can occupy 30–40% of cell volume.
Functions:
• Stores water and ions.
• Maintains turgor pressure to keep plant cells upright against the cell wall.
Cytoskeleton components and functions:
Components:
• Microtubules, actin filaments, intermediate filaments.
Functions:
• Maintains cell shape.
• Organizes organelles and cell parts.
• Enables cell movement and division.
Microtubules structure and functions:
Structure: Polymers of tubulin protein.
Function:
• Component of the cytoskeleton.
• Used for intercellular transport of organelles.
• Separate chromosomes during mitosis.
Centrioles structure and function:
Structure:
• Paired, cylindrical organelles.
• Composed of 9 groups of 3 microtubules with radial symmetry.
Function:
• Organize mitotic spindle during cell division.
• Anchor microtubules in cytoplasm, cilia, and flagella.
Cilia and flagella a structure and function:
Structure:
• Extensions of the cell surface.
• Formed from modified centrioles called a basal body
Function: Aid in cell movement.
CILIA:
• Short and numerous.
• Beat in coordinated waves.
FLAGELLA:
• Longer, usually 1 or 2 per cell.
• Move independently.
Cell wall structure and function
• Structure:
– Found in plants, fungi, and bacteria (not animals)
– Made of cellulose (plants), chitin (fungi), or peptidoglycan (bacteria)
– Rigid layer outside the plasma membrane
• Function:
– Supports the cell and maintains shape
– Protects from bursting (osmosis)
– Fully permeable (doesn’t control what enters/leaves)
Microvilli structure and function:
Structure:
– Tiny finger-like extensions of the cell membrane
– Contain actin filaments
– Found on cells in intestines and kidneys
• Function:
– Increase surface area for absorption
– Help absorb nutrients and fluids faster
Plasma membrane function and structure
Structure:
– Phospholipid bilayer with proteins
– Has cholesterol, proteins, and carbohydrates
– Flexible and semi-permeable
• Function:
– Controls what enters and leaves the cell
– Helps with communication and cell recognition
– Used in transport, signaling, and membrane fusion (endocytosis/exocytosis)
